pactions report error when argument has no action and target

Error message are:
error: error: Execution was interrupted, reason: Attempted to dereference an invalid ObjC Object or send it an unrecognized selector.
The process has been returned to the state before expression evaluation.
error: error: use of undeclared identifier 'None'
Traceback (most recent call last):
File "/usr/local/Cellar/chisel/1.5.0/libexec/fblldb.py", line 83, in runCommand
command.run(args, options)
File "/usr/local/Cellar/chisel/1.5.0/libexec/commands/FBPrintCommands.py", line 449, in run
targetCount = fb.evaluateIntegerExpression('[{targets} count]'.format(targets=targets))
File "/usr/local/Cellar/chisel/1.5.0/libexec/fblldbbase.py", line 76, in evaluateIntegerExpression
output = evaluateExpression('(int)(' + expression + ')', printErrors).replace('\'', '')
AttributeError: 'NoneType' object has no attribute 'replace'